Inventory system with efficient operator handling of inventory items

ABSTRACT

An inventory system can include multiple floors. The system can assign operations involving inventory items to a floor based on information about the floor, other floors, the operations, and/or the inventory items. In one example, the system may assign an order to be assembled on a floor based on the floor containing items for the order. Items may be moved to the floor from other floors to complete the order. In another example, a receipt receptacle received from a shipping vehicle can be moved to a rack without separating inventory items from the receipt vehicle. A mobile drive unit can move the rack to a floor based on information known about the inventory items matching criteria about the floor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/552,334, filed Nov. 24, 2014, entitled “INVENTORY SYSTEM WITHEFFICIENT OPERATOR HANDLING OF INVENTORY ITEMS”, and issued as U.S. Pat.No. 9,809,384 on Nov. 7, 2017, the contents of which are hereinincorporated in its entirety.

BACKGROUND

Modern inventory systems, such as those in mail order warehouses, supplychain distribution centers, airport luggage systems, and custom-ordermanufacturing facilities, face significant challenges in responding torequests for inventory items. As inventory systems grow, the challengesof simultaneously completing a large number of packing, storing, andother inventory-related tasks become non-trivial. In inventory systemstasked with responding to large numbers of diverse inventory requests,inefficient utilization of system resources, including space, equipment,and manpower, can result in lower throughput, unacceptably long responsetimes, an ever-increasing backlog of unfinished tasks, and, in general,poor system performance. Additionally, expanding or reducing the size orcapabilities of many inventory systems requires significant changes toexisting infrastructure and equipment. As a result, the cost ofincremental changes to capacity or functionality may be prohibitivelyexpensive, limiting the ability of the system to accommodatefluctuations in system throughput.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, in which:

FIG. 1 illustrates an example of a multi-level inventory systemaccording to a particular embodiment;

FIG. 2 illustrates components of an example of an inventory systemaccording to a particular embodiment;

FIG. 3 illustrates in greater detail the components of an examplemanagement module that may be utilized in particular embodiments of theinventory system shown in FIG. 2;

FIGS. 4 and 5 illustrate in greater detail an example mobile drive unitthat may be utilized in particular embodiments of the inventory systemshown in FIG. 2;

FIG. 6 illustrates in greater detail an example inventory holder thatmay be utilized in particular embodiments of the inventory system shownin FIG. 2;

FIG. 7 is a process flow illustrating an example process that can beperformed in the inventory system according to a particular embodiment;

FIG. 8 illustrates a perspective view of an example check-in stationaccording to a particular embodiment;

FIG. 9 illustrates another example of a check-in station according to aparticular embodiment;

FIG. 10 illustrates a perspective view of an example of a receivingstation in accordance with a particular embodiment;

FIG. 11 illustrates a perspective view of an example of a pick-to-orderstation in accordance with a particular embodiment;

FIG. 12 illustrates a perspective view of an example of a ship stationin accordance with a particular embodiment; and

FIG. 13 illustrates an environment in which various features of theinventory system can be implemented, in accordance with at least oneembodiment.

DETAILED DESCRIPTION

In the following description, various embodiments will be described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will also be apparent to one skilled in the art that theembodiments may be practiced without the specific details. Furthermore,well-known features may be omitted or simplified in order not to obscurethe embodiment being described.

Embodiments herein are directed to an inventory system having multipleinventory holders and drive units for moving the inventory holders.Specifically, features herein are directed to utilizing mobile driveunits to facilitate efficient operator handling of inventory items beingprocessed through an inventory system, which may be distributed acrossmultiple contemporaneously-operating floors of a common workspace. Inone example, cases of inbound inventory items from delivery vehicles canbe loaded onto shuttles—without sorting the content of the cases—andmoved by the mobile drive units to a holding area from which individualcases can be accessed and/or processed in a sequence that is notrestricted to the sequence in which the cases were removed from thedelivery vehicles. In another example, mobile drive units can be used tospread inventory among multiple vertically separated floors so that thefloors can operate separately and collectively for efficient fulfillmentof orders.

As an illustrative example showing these and other features, FIG. 1illustrates an example of a multi-level inventory system 10 according toa particular embodiment. The inventory system 10 can include featuresdescribed in greater detail beginning in FIG. 2 below. The inventorysystem 10 can utilize mobile drive units 20 to facilitate strategicoperator interactions with inventory items passing through the inventorysystem 10. For example, the mobile drive units 20 can move inventoryholders 30 loaded with items between different stations 50 at whichoperators may “touch” inventory items and prepare the inventory itemsfor subsequent phases in the inventory system 10. The mobile drive units20 may facilitate an efficient amount of touches and reduce a totalnumber of touches and/or time consumed by touches. The system 10 caninclude stations 50 that facilitate strategic touches.

At a first, “check in” station 50C, inventory items can be checked intothe inventory system 10. The items may arrive in boxes or othercontainers (hereinafter “cases” or “receipt receptacles”) carried bytrucks or other delivery vehicles. The cases can be loaded directly ontoracks 30, e.g., case shuttles 32 (FIG. 7), at the check-in station 50Cwithout any sortation of the items contained therein. In someembodiments, the cases may be scanned or otherwise identified duringcheck-in. The racks with the cases of inventory items can be moved bymobile drive units 20 away from the check-in station 50C, such as to astorage area 108 on any level W, X, Y, or Z of the workspace 70. Forexample, the mobile drive unit 20 can move a rack 30 to a storage area108 on a floor in order to improve a mix of inventory items on the floorbased on the items known to be on the floor and the items known to be inthe cases on the rack 30. Mobile drive units 20 can move racks 30between levels W, X, Y, or Z of the workspace 70 using verticalconveyance mechanisms, e.g., elevators 80.

A mobile drive unit 20 can move a rack 30 carrying cases of inventoryitems to any receiving station 50R on any floor W, X, Y, or Z, such asfrom a storage area 108 on any floor or from a check-in station 50C. Insome embodiments, a rack 30 carrying cases may be moved to a receivestation 50R in a different order than cases are loaded onto the rack. Insome embodiments, the rack is not moved to the receive station 50R untilan order is placed for an item in a case. At the receive station 50R, acase can be removed from the rack so that inventory items in the casecan be sorted and placed into other racks 30, e.g., pickable inventoryholders 34 (FIG. 7). Such a touch can make inventory items “pickable,”e.g., ready to be picked from inventory holders 30 to fulfill orders. Amobile drive unit 20 can move a pickable inventory holder 30 away fromthe receive station 50R, such as to a storage area 108 on any one of thefloors W, X, Y, or Z.

A mobile drive unit can move a pickable inventory holder 30 to a pickstation 50P, such as from a storage area 108 on one of the levels, W, X,Y, or Z, and/or from a receive station 50R. At the pick station 50P,inventory items can be removed from the inventory holders, e.g.,pickable inventory holders 34 and/or case shuttles 32, and thentransferred into cases (such as order receptacles 514 or 514′ (FIG. 11)that may be filled with items to fulfill orders) that are loaded ontofurther racks 30, e.g., order shuttles 36 (FIG. 7). Such a touch mayswitch inventory items from a pickable state directly to an assembledorder state without any additional conveyance and/or touches forintermediate sorting and/or packing operations. Mobile drive unit 20 canmove an inventory holder or other rack 30 with assembled orders from thepick station 50P, such as to a storage area 108 on any of the levels W,X, Y, or Z, and/or to a ship station 50S.

At the ship station 50S, orders can be transferred from a rack 30 into adelivery truck or other vehicle to transport the ordered items and theircases away from the building and to ultimate destinations.

Although FIG. 1 for the sake of clarity shows a uniform type ofinventory holder 30 and a uniform type of mobile drive unit 20throughout the various phases of the inventory system 10, in someembodiments, different types of mobile drive units 20 and/or differenttypes of inventory holders 30 may be utilized in various phases. As anillustrative example, larger mobile drive units 20 with a greaterlifting capacity may be utilized to handle inventory holders 30, e.g.,case shuttles 32 and order shuttles 36, relative to check-in stations50C and/or shipping stations 50S, and more agile, smaller mobile driveunits 20 may handle inventory holders 30, e.g., pickable inventoryholders 34, with respect to receiving stations 50R and/or pick stations50P. In some embodiments, inventory holders 30 may be configured as—orreplaced with—structures particularly suited for one or more specificphases, such as the case shuttles 32, pickable inventory holders 34,and/or order shuttles 36 described in greater detail below with respectto FIG. 7 and subsequent drawings.

FIG. 2 illustrates the contents of an example of an inventory system 10.Inventory system 10 includes a management module 15, one or more mobiledrive units 20, one or more inventory holders 30, and one or moreinventory stations 50. Mobile drive units 20 transport inventory holders30 between points within a workspace 70 in response to commandscommunicated by management module 15. Each inventory holder 30 storesone or more types of inventory items. As a result, inventory system 10is capable of moving inventory items between locations within workspace70 to facilitate the entry, processing, and/or removal of inventoryitems from inventory system 10 and the completion of other tasksinvolving inventory items.

Management module 15 assigns tasks to appropriate components ofinventory system 10 and coordinates operation of the various componentsin completing the tasks. These tasks may relate not only to the movementand processing of inventory items, but also to the management andmaintenance of the components of inventory system 10. For example,management module 15 may assign portions of workspace 70 as parkingspaces for mobile drive units 20, the scheduled recharge or replacementof mobile drive unit batteries, the storage of empty inventory holders30, or any other operations associated with the functionality supportedby inventory system 10 and its various components. Management module 15may select components of inventory system 10 to perform these tasks andcommunicate appropriate commands and/or data to the selected componentsto facilitate completion of these operations. Although shown in FIG. 2as a single, discrete component, management module 15 may representmultiple components and may represent or include portions of mobiledrive units 20 or other elements of inventory system 10. As a result,any or all of the interaction between a particular mobile drive unit 20and management module 15 that is described below may, in particularembodiments, represent peer-to-peer communication between that mobiledrive unit 20 and one or more other mobile drive units 20. The contentsand operation of an example embodiment of management module 15 arediscussed further below with respect to FIG. 3.

Mobile drive units 20 move inventory holders 30 between locations withinworkspace 70. Mobile drive units 20 may represent any devices orcomponents appropriate for use in inventory system 10 based on thecharacteristics and configuration of inventory holders 30 and/or otherelements of inventory system 10. In a particular embodiment of inventorysystem 10, mobile drive units 20 represent independent, self-powereddevices configured to freely move about workspace 70. Examples of suchinventory systems are disclosed in U.S. Patent Publication No.2012/0143427, published on Jun. 7, 2012, titled “SYSTEM AND METHOD FORPOSITIONING A MOBILE DRIVE UNIT” and U.S. Pat. No. 8,280,547, issued onOct. 2, 2012, titled “METHOD AND SYSTEM FOR TRANSPORTING INVENTORYITEMS”, the entire disclosures of which are herein incorporated byreference. In alternative embodiments, mobile drive units 20 representelements of a tracked inventory system configured to move inventoryholder 30 along tracks, rails, cables, crane system, or other guidanceor support elements traversing workspace 70. In such an embodiment,mobile drive units 20 may receive power and/or support through aconnection to the guidance elements, such as a powered rail.Additionally, in particular embodiments of inventory system 10 mobiledrive units 20 may be configured to utilize alternative conveyanceequipment to move within workspace 70 and/or between separate portionsof workspace 70. The contents and operation of an example embodiment ofa mobile drive unit 20 are discussed further below with respect to FIGS.4 and 5.

Additionally, mobile drive units 20 may be capable of communicating withmanagement module 15 to receive information identifying selectedinventory holders 30, transmit the locations of mobile drive units 20,or exchange any other suitable information to be used by managementmodule 15 or mobile drive units 20 during operation. Mobile drive units20 may communicate with management module 15 wirelessly, using wiredconnections between mobile drive units 20 and management module 15,and/or in any other appropriate manner. As one example, particularembodiments of mobile drive unit 20 may communicate with managementmodule 15 and/or with one another using 802.11, Bluetooth, or InfraredData Association (IrDA) standards, or any other appropriate wirelesscommunication protocol. As another example, in a tracked inventorysystem 10, tracks or other guidance elements upon which mobile driveunits 20 move may be wired to facilitate communication between mobiledrive units 20 and other components of inventory system 10. Furthermore,as noted above, management module 15 may include components ofindividual mobile drive units 20. Thus, for the purposes of thisdescription and the claims that follow, communication between managementmodule 15 and a particular mobile drive unit 20 may representcommunication between components of a particular mobile drive unit 20.In general, mobile drive units 20 may be powered, propelled, andcontrolled in any manner appropriate based on the configuration andcharacteristics of inventory system 10.

Inventory holders 30 store inventory items. In a particular embodiment,inventory holders 30 include multiple storage bins with each storage bincapable of holding one or more types of inventory items. Inventoryholders 30 are capable of being carried, rolled, and/or otherwise movedby mobile drive units 20. In particular embodiments, inventory holder 30may provide additional propulsion to supplement that provided by mobiledrive unit 20 when moving inventory holder 30.

Additionally, in particular embodiments, inventory items 40 may alsohang from hooks or bars (not shown) within or on inventory holder 30. Ingeneral, inventory holder 30 may store inventory items 40 in anyappropriate manner within inventory holder 30 and/or on the externalsurface of inventory holder 30.

Additionally, each inventory holder 30 may include a plurality of faces,and each bin may be accessible through one or more faces of theinventory holder 30. For example, in a particular embodiment, inventoryholder 30 includes four faces. In such an embodiment, bins located at acorner of two faces may be accessible through either of those two faces,while each of the other bins is accessible through an opening in one ofthe four faces. Mobile drive unit 20 may be configured to rotateinventory holder 30 at appropriate times to present a particular faceand the bins associated with that face to an operator or othercomponents of inventory system 10.

Inventory items represent any objects suitable for storage, retrieval,and/or processing in an automated inventory system 10. For the purposesof this description, “inventory items” may represent any one or moreobjects of a particular type that are stored in inventory system 10.Thus, a particular inventory holder 30 is currently “storing” aparticular inventory item if the inventory holder 30 currently holds oneor more units of that type. As one example, inventory system 10 mayrepresent a mail order warehouse facility, and inventory items mayrepresent merchandise stored in the warehouse facility. Duringoperation, mobile drive units 20 may retrieve inventory holders 30containing one or more inventory items requested in an order to bepacked for delivery to a customer or inventory holders 30 carryingpallets containing aggregated collections of inventory items forshipment. Moreover, in particular embodiments of inventory system 10,boxes containing completed orders may themselves represent inventoryitems.

In particular embodiments, inventory system 10 may also include one ormore inventory stations 50. Inventory stations 50 represent locationsdesignated for the completion of particular tasks involving inventoryitems. Such tasks may include the removal of inventory items frominventory holders 30, the introduction of inventory items into inventoryholders 30, the counting of inventory items in inventory holders 30, thedecomposition of inventory items (e.g. from pallet- or case-sized groupsto individual inventory items), the consolidation of inventory itemsbetween inventory holders 30, and/or the processing or handling ofinventory items in any other suitable manner. In particular embodiments,inventory stations 50 may just represent the physical locations where aparticular task involving inventory items can be completed withinworkspace 70. In alternative embodiments, inventory stations 50 mayrepresent both the physical location and also any appropriate equipmentfor processing or handling inventory items, such as scanners formonitoring the flow of inventory items in and out of inventory system10, communication interfaces for communicating with management module15, and/or any other suitable components. Inventory stations 50 may becontrolled, entirely or in part, by human operators or may be fullyautomated. Moreover, the human or automated operators of inventorystations 50 may be capable of performing certain tasks to inventoryitems, such as packing, counting, or transferring inventory items, aspart of the operation of inventory system 10.

Workspace 70 represents an area associated with inventory system 10 inwhich mobile drive units 20 can move and/or inventory holders 30 can bestored. For example, workspace 70 may represent all or part of the floorof a mail-order warehouse in which inventory system 10 operates.Although FIG. 2 shows, for the purposes of illustration, an embodimentof inventory system 10 in which workspace 70 includes a fixed,predetermined, and finite physical space, particular embodiments ofinventory system 10 may include mobile drive units 20 and inventoryholders 30 that are configured to operate within a workspace 70 that isof variable dimensions and/or an arbitrary geometry. While FIG. 2illustrates a particular embodiment of inventory system 10 in whichworkspace 70 is entirely enclosed in a building, alternative embodimentsmay utilize workspaces 70 in which some or all of the workspace 70 islocated outdoors, within a vehicle (such as a cargo ship), or otherwiseunconstrained by any fixed structure.

In operation, management module 15 selects appropriate components tocomplete particular tasks and transmits task assignments 18 to theselected components to trigger completion of the relevant tasks. Eachtask assignment 18 defines one or more tasks to be completed by aparticular component. These tasks may relate to the retrieval, storage,replenishment, and counting of inventory items and/or the management ofmobile drive units 20, inventory holders 30, inventory stations 50 andother components of inventory system 10. Depending on the component andthe task to be completed, a particular task assignment 18 may identifylocations, components, and/or actions associated with the correspondingtask and/or any other appropriate information to be used by the relevantcomponent in completing the assigned task.

In particular embodiments, management module 15 generates taskassignments 18 based, in part, on inventory requests that managementmodule 15 receives from other components of inventory system 10 and/orfrom external components in communication with management module 15.These inventory requests identify particular operations to be completedinvolving inventory items stored or to be stored within inventory system10 and may represent communication of any suitable form. For example, inparticular embodiments, an inventory request may represent a shippingorder specifying particular inventory items that have been purchased bya customer and that are to be retrieved from inventory system 10 forshipment to the customer. Management module 15 may also generate taskassignments 18 independently of such inventory requests, as part of theoverall management and maintenance of inventory system 10. For example,management module 15 may generate task assignments 18 in response to theoccurrence of a particular event (e.g., in response to a mobile driveunit 20 requesting a space to park), according to a predeterminedschedule (e.g., as part of a daily start-up routine), or at anyappropriate time based on the configuration and characteristics ofinventory system 10. After generating one or more task assignments 18,management module 15 transmits the generated task assignments 18 toappropriate components for completion of the corresponding task. Therelevant components then execute their assigned tasks.

With respect to mobile drive units 20 specifically, management module 15may, in particular embodiments, communicate task assignments 18 toselected mobile drive units 20 that identify one or more destinationsfor the selected mobile drive units 20. Management module 15 may selecta mobile drive unit 20 to assign the relevant task based on the locationor state of the selected mobile drive unit 20, an indication that theselected mobile drive unit 20 has completed a previously-assigned task,a predetermined schedule, and/or any other suitable consideration. Thesedestinations may be associated with an inventory request the managementmodule 15 is executing or a management objective the management module15 is attempting to fulfill. For example, the task assignment may definethe location of an inventory holder 30 to be retrieved, an inventorystation 50 to be visited, a storage location where the mobile drive unit20 should park until receiving another task, or a location associatedwith any other task appropriate based on the configuration,characteristics, and/or state of inventory system 10, as a whole, orindividual components of inventory system 10. For example, in particularembodiments, such decisions may be based on the popularity of particularinventory items, the staffing of a particular inventory station 50, thetasks currently assigned to a particular mobile drive unit 20, and/orany other appropriate considerations.

As part of completing these tasks mobile drive units 20 may dock withand transport inventory holders 30 within workspace 70. Mobile driveunits 20 may dock with inventory holders 30 by connecting to, lifting,and/or otherwise interacting with inventory holders 30 in any othersuitable manner so that, when docked, mobile drive units 20 are coupledto and/or support inventory holders 30 and can move inventory holders 30within workspace 70. While the description below focuses on particularembodiments of mobile drive unit 20 and inventory holder 30 that areconfigured to dock in a particular manner, alternative embodiments ofmobile drive unit 20 and inventory holder 30 may be configured to dockin any manner suitable to allow mobile drive unit 20 to move inventoryholder 30 within workspace 70. Additionally, as noted below, inparticular embodiments, mobile drive units 20 represent all or portionsof inventory holders 30. In such embodiments, mobile drive units 20 maynot dock with inventory holders 30 before transporting inventory holders30 and/or mobile drive units 20 may each remain continually docked witha particular inventory holder 30.

While the appropriate components of inventory system 10 completeassigned tasks, management module 15 may interact with the relevantcomponents to ensure the efficient use of space, equipment, manpower,and other resources available to inventory system 10. As one specificexample of such interaction, management module 15 is responsible, inparticular embodiments, for planning the paths mobile drive units 20take when moving within workspace 70 and for allocating use of aparticular portion of workspace 70 to a particular mobile drive unit 20for purposes of completing an assigned task. In such embodiments, mobiledrive units 20 may, in response to being assigned a task, request a pathto a particular destination associated with the task. Moreover, whilethe description below focuses on one or more embodiments in which mobiledrive unit 20 requests paths from management module 15, mobile driveunit 20 may, in alternative embodiments, generate its own paths.

Components of inventory system 10 may provide information to managementmodule 15 regarding their current state, other components of inventorysystem 10 with which they are interacting, and/or other conditionsrelevant to the operation of inventory system 10. This may allowmanagement module 15 to utilize feedback from the relevant components toupdate algorithm parameters, adjust policies, or otherwise modify itsdecision-making to respond to changes in operating conditions or theoccurrence of particular events.

In addition, while management module 15 may be configured to managevarious aspects of the operation of the components of inventory system10, in particular embodiments, the components themselves may also beresponsible for decision-making relating to certain aspects of theiroperation, thereby reducing the processing load on management module 15.

Thus, based on its knowledge of the location, current state, and/orother characteristics of the various components of inventory system 10and an awareness of all the tasks currently being completed, managementmodule 15 can generate tasks, allot usage of system resources, andotherwise direct the completion of tasks by the individual components ina manner that optimizes operation from a system-wide perspective.Moreover, by relying on a combination of both centralized, system-widemanagement and localized, component-specific decision-making, particularembodiments of inventory system 10 may be able to support a number oftechniques for efficiently executing various aspects of the operation ofinventory system 10. As a result, particular embodiments of managementmodule 15 may, by implementing one or more management techniquesdescribed below, enhance the efficiency of inventory system 10 and/orprovide other operational benefits.

FIG. 3 illustrates in greater detail the components of a particularembodiment of management module 15. As shown, the example embodimentincludes a resource scheduling module 92, a route planning module 94, asegment reservation module 96, an inventory module 97, a communicationinterface module 98, a processor 90, and a memory 91. Management module15 may represent a single component, multiple components located at acentral location within inventory system 10, or multiple componentsdistributed throughout inventory system 10. For example, managementmodule 15 may represent components of one or more mobile drive units 20that are capable of communicating information between the mobile driveunits 20 and coordinating the movement of mobile drive units 20 withinworkspace 70. In general, management module 15 may include anyappropriate combination of hardware and/or software suitable to providethe described functionality.

Processor 90 is operable to execute instructions associated with thefunctionality provided by management module 15. Processor 90 maycomprise one or more general purpose computers, dedicatedmicroprocessors, or other processing devices capable of communicatingelectronic information. Examples of processor 90 include one or moreapplication-specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), digital signal processors (DSPs) and any othersuitable specific or general purpose processors.

Memory 91 stores processor instructions, inventory requests, reservationinformation, state information for the various components of inventorysystem 10 and/or any other appropriate values, parameters, orinformation utilized by management module 15 during operation. Memory 91may represent any collection and arrangement of volatile or nonvolatile,local or remote devices suitable for storing data. Examples of memory 91include, but are not limited to, random access memory (RAM) devices,read only memory (ROM) devices, magnetic storage devices, opticalstorage devices or any other suitable data storage devices.

Resource scheduling module 92 processes received inventory requests andgenerates one or more assigned tasks to be completed by the componentsof inventory system 10. Resource scheduling module 92 may also selectone or more appropriate components for completing the assigned tasksand, using communication interface module 98, communicate the assignedtasks to the relevant components. Additionally, resource schedulingmodule 92 may also be responsible for generating assigned tasksassociated with various management operations, such as prompting mobiledrive units 20 to recharge batteries or have batteries replaced,instructing inactive mobile drive units 20 to park in a location outsidethe anticipated traffic flow or a location near the anticipated site offuture tasks, and/or directing mobile drive units 20 selected for repairor maintenance to move towards a designated maintenance station.

Route planning module 94 receives route requests from mobile drive units20. These route requests identify one or more destinations associatedwith a task the requesting mobile drive unit 20 is executing. Inresponse to receiving a route request, route planning module 94generates a path to one or more destinations identified in the routerequest. Route planning module 94 may implement any appropriatealgorithms utilizing any appropriate parameters, factors, and/orconsiderations to determine the appropriate path. After generating anappropriate path, route planning module 94 transmits a route responseidentifying the generated path to the requesting mobile drive unit 20using communication interface module 98.

Segment reservation module 96 receives reservation requests from mobiledrive units 20 attempting to move along paths generated by routeplanning module 94. These reservation requests request the use of aparticular portion of workspace 70 (referred to herein as a “segment”)to allow the requesting mobile drive unit 20 to avoid collisions withother mobile drive units 20 while moving across the reserved segment. Inresponse to received reservation requests, segment reservation module 96transmits a reservation response granting or denying the reservationrequest to the requesting mobile drive unit 20 using the communicationinterface module 98.

The inventory module 97 maintains information about the location andnumber of inventory items 40 in the inventory system 10. Information canbe maintained about the number of inventory items 40 in a particularinventory holder 30, and the maintained information can include thelocation of those inventory items 40 in the inventory holder 30. Theinventory module 97 can also communicate with the mobile drive units 20,utilizing task assignments 18 to maintain, replenish or move inventoryitems 40 within the inventory system 10.

Communication interface module 98 facilitates communication betweenmanagement module 15 and other components of inventory system 10,including reservation responses, reservation requests, route requests,route responses, and task assignments. These reservation responses,reservation requests, route requests, route responses, and taskassignments may represent communication of any form appropriate based onthe capabilities of management module 15 and may include any suitableinformation. Depending on the configuration of management module 15,communication interface module 98 may be responsible for facilitatingeither or both of wired and wireless communication between managementmodule 15 and the various components of inventory system 10. Inparticular embodiments, management module 15 may communicate usingcommunication protocols such as 802.11, Bluetooth, or Infrared DataAssociation (IrDA) standards. Furthermore, management module 15 may, inparticular embodiments, represent a portion of mobile drive unit 20 orother components of inventory system 10. In such embodiments,communication interface module 98 may facilitate communication betweenmanagement module 15 and other parts of the same system component.

In general, resource scheduling module 92, route planning module 94,segment reservation module 96, inventory module 97, and communicationinterface module 98 may each represent any appropriate hardware and/orsoftware suitable to provide the described functionality. In addition,as noted above, management module 15 may, in particular embodiments,represent multiple different discrete components and any or all ofresource scheduling module 92, route planning module 94, segmentreservation module 96, inventory module 97, and communication interfacemodule 98 may represent components physically separate from theremaining elements of management module 15. Moreover, any two or more ofresource scheduling module 92, route planning module 94, segmentreservation module 96, inventory module 97, and communication interfacemodule 98 may share common components. For example, in particularembodiments, resource scheduling module 92, route planning module 94,segment reservation module 96, and inventory module 97 representcomputer processes executing on processor 90 and communication interfacemodule 98 comprises a wireless transmitter, a wireless receiver, and arelated computer process executing on processor 90.

FIGS. 4 and 5 illustrate in greater detail the components of aparticular embodiment of mobile drive unit 20. In particular, FIGS. 4and 5 include a front and side view of an example mobile drive unit 20.Mobile drive unit 20 includes a docking head 110, a drive module 120, adocking actuator 130, and a control module 170. Additionally, mobiledrive unit 20 may include one or more sensors configured to detect ordetermine the location of mobile drive unit 20, inventory holder 30,and/or other appropriate elements of inventory system 10. In theillustrated embodiment, mobile drive unit 20 includes a position sensor140, a holder sensor 150, an obstacle sensor 160, and an identificationsignal transmitter 162.

Docking head 110, in particular embodiments of mobile drive unit 20,couples mobile drive unit 20 to inventory holder 30 and/or supportsinventory holder 30 when mobile drive unit 20 is docked to inventoryholder 30. Docking head 110 may additionally allow mobile drive unit 20to maneuver inventory holder 30, such as by lifting inventory holder 30,propelling inventory holder 30, rotating inventory holder 30, and/ormoving inventory holder 30 in any other appropriate manner. Docking head110 may also include any appropriate combination of components, such asribs, spikes, and/or corrugations, to facilitate such manipulation ofinventory holder 30. For example, in particular embodiments, dockinghead 110 may include a high-friction portion that abuts a portion ofinventory holder 30 while mobile drive unit 20 is docked to inventoryholder 30. In such embodiments, frictional forces created between thehigh-friction portion of docking head 110 and a surface of inventoryholder 30 may induce translational and rotational movement in inventoryholder 30 when docking head 110 moves and rotates, respectively. As aresult, mobile drive unit 20 may be able to manipulate inventory holder30 by moving or rotating docking head 110, either independently or as apart of the movement of mobile drive unit 20 as a whole.

Drive module 120 propels mobile drive unit 20 and, when mobile driveunit 20 and inventory holder 30 are docked, inventory holder 30. Drivemodule 120 may represent any appropriate collection of componentsoperable to propel mobile drive unit 120. For example, in theillustrated embodiment, drive module 120 includes motorized axle 122, apair of motorized wheels 124, and a pair of stabilizing wheels 126. Onemotorized wheel 124 is located at each end of motorized axle 122, andone stabilizing wheel 126 is positioned at each end of mobile drive unit20.

Docking actuator 130 moves docking head 110 towards inventory holder 30to facilitate docking of mobile drive unit 20 and inventory holder 30.Docking actuator 130 may also be capable of adjusting the position ororientation of docking head 110 in other suitable manners to facilitatedocking. Docking actuator 130 may include any appropriate components,based on the configuration of mobile drive unit 20 and inventory holder30, for moving docking head 110 or otherwise adjusting the position ororientation of docking head 110. For example, in the illustratedembodiment, docking actuator 130 includes a motorized shaft (not shown)attached to the center of docking head 110. The motorized shaft isoperable to lift docking head 110 as appropriate for docking withinventory holder 30.

Drive module 120 may be configured to propel mobile drive unit 20 in anyappropriate manner. For example, in the illustrated embodiment,motorized wheels 124 are operable to rotate in a first direction topropel mobile drive unit 20 in a forward direction. Motorized wheels 124are also operable to rotate in a second direction to propel mobile driveunit 20 in a backward direction. In the illustrated embodiment, drivemodule 120 is also configured to rotate mobile drive unit 20 by rotatingmotorized wheels 124 in different directions from one another or byrotating motorized wheels 124 at different speeds from one another.

Position sensor 140 represents one or more sensors, detectors, or othercomponents suitable for determining the location of mobile drive unit 20in any appropriate manner. For example, in particular embodiments, theworkspace 70 associated with inventory system 10 includes a number offiducial marks that mark points on a two-dimensional grid that coversall or a portion of workspace 70. In such embodiments, position sensor140 may include a camera and suitable image- and/or video-processingcomponents, such as an appropriately-programmed digital signalprocessor, to allow position sensor 140 to detect fiducial marks withinthe camera's field of view. Control module 170 may store locationinformation that position sensor 140 updates as position sensor 140detects fiducial marks. As a result, position sensor 140 may utilizefiducial marks to maintain an accurate indication of the location mobiledrive unit 20 and to aid in navigation when moving within workspace 70.

Holder sensor 150 represents one or more sensors, detectors, or othercomponents suitable for detecting inventory holder 30 and/ordetermining, in any appropriate manner, the location of inventory holder30, as an absolute location or as a position relative to mobile driveunit 20. Holder sensor 150 may be capable of detecting the location of aparticular portion of inventory holder 30 or inventory holder 30 as awhole. Mobile drive unit 20 may then use the detected information fordocking with or otherwise interacting with inventory holder 30.

Obstacle sensor 160 represents one or more sensors capable of detectingobjects located in one or more different directions in which mobiledrive unit 20 is capable of moving. Obstacle sensor 160 may utilize anyappropriate components and techniques, including optical, radar, sonar,pressure-sensing and/or other types of detection devices appropriate todetect objects located in the direction of travel of mobile drive unit20. In particular embodiments, obstacle sensor 160 may transmitinformation describing objects it detects to control module 170 to beused by control module 170 to identify obstacles and to take appropriateremedial actions to prevent mobile drive unit 20 from colliding withobstacles and/or other objects.

Obstacle sensor 160 may also detect signals transmitted by other mobiledrive units 20 operating in the vicinity of the illustrated mobile driveunit 20. For example, in particular embodiments of inventory system 10,one or more mobile drive units 20 may include an identification signaltransmitter 162 that transmits a drive identification signal. The driveidentification signal indicates to other mobile drive units 20 that theobject transmitting the drive identification signal is in fact a mobiledrive unit. Identification signal transmitter 162 may be capable oftransmitting infrared, ultraviolet, audio, visible light, radio, and/orother suitable signals that indicate to recipients that the transmittingdevice is a mobile drive unit 20.

Additionally, in particular embodiments, obstacle sensor 160 may also becapable of detecting state information transmitted by other mobile driveunits 20. For example, in particular embodiments, identification signaltransmitter 162 may be capable of including state information relatingto mobile drive unit 20 in the transmitted identification signal. Thisstate information may include, but is not limited to, the position,velocity, direction, and the braking capabilities of the transmittingmobile drive unit 20. In particular embodiments, mobile drive unit 20may use the state information transmitted by other mobile drive units toavoid collisions when operating in close proximity with those othermobile drive units.

Control module 170 monitors and/or controls operation of drive module120 and docking actuator 130. Control module 170 may also receiveinformation from sensors such as position sensor 140 and holder sensor150 and adjust the operation of drive module 120, docking actuator 130,and/or other components of mobile drive unit 20 based on thisinformation. Additionally, in particular embodiments, mobile drive unit20 may be configured to communicate with a management device ofinventory system 10 and control module 170 may receive commandstransmitted to mobile drive unit 20 and communicate information back tothe management device utilizing appropriate communication components ofmobile drive unit 20. Control module 170 may include any appropriatehardware and/or software suitable to provide the describedfunctionality. In particular embodiments, control module 170 includes ageneral-purpose microprocessor programmed to provide the describedfunctionality. Additionally, control module 170 may include all orportions of docking actuator 130, drive module 120, position sensor 140,and/or holder sensor 150, and/or share components with any of theseelements of mobile drive unit 20.

Moreover, in particular embodiments, control module 170 may includehardware and software located in components that are physically distinctfrom the device that houses drive module 120, docking actuator 130,and/or the other components of mobile drive unit 20 described above. Forexample, in particular embodiments, each mobile drive unit 20 operatingin inventory system 10 may be associated with a software process(referred to here as a “drive agent”) operating on a server that is incommunication with the device that houses drive module 120, dockingactuator 130, and other appropriate components of mobile drive unit 20.This drive agent may be responsible for requesting and receiving tasks,requesting and receiving routes, transmitting state informationassociated with mobile drive unit 20, and/or otherwise interacting withmanagement module 15 and other components of inventory system 10 onbehalf of the device that physically houses drive module 120, dockingactuator 130, and the other appropriate components of mobile drive unit20. As a result, for the purposes of this description and the claimsthat follow, the term “mobile drive unit” includes software and/orhardware, such as agent processes, that provides the describedfunctionality on behalf of mobile drive unit 20 but that may be locatedin physically distinct devices from the drive module 120, dockingactuator 130, and/or the other components of mobile drive unit 20described above.

While FIGS. 4 and 5 illustrate a particular embodiment of mobile driveunit 20 containing certain components and configured to operate in aparticular manner, mobile drive unit 20 may represent any appropriatecomponent and/or collection of components configured to transport and/orfacilitate the transport of inventory holders 30. As another example,mobile drive unit 20 may represent part of an overhead crane system inwhich one or more crane assemblies are capable of moving within anetwork of wires or rails to a position suitable to dock with aparticular inventory holder 30. After docking with inventory holder 30,the crane assembly may then lift inventory holder 30 and move inventoryto another location for purposes of completing an assigned task.

Furthermore, in particular embodiments, mobile drive unit 20 mayrepresent all or a portion of inventory holder 30. Inventory holder 30may include motorized wheels or any other components suitable to allowinventory holder 30 to propel itself. As one specific example, a portionof inventory holder 30 may be responsive to magnetic fields. Inventorysystem 10 may be able to generate one or more controlled magnetic fieldscapable of propelling, maneuvering and/or otherwise controlling theposition of inventory holder 30 as a result of the responsive portion ofinventory holder 30. In such embodiments, mobile drive unit 20 mayrepresent the responsive portion of inventory holder 30 and/or thecomponents of inventory system 10 responsible for generating andcontrolling these magnetic fields. While this description providesseveral specific examples, mobile drive unit 20 may, in general,represent any appropriate component and/or collection of componentsconfigured to transport and/or facilitate the transport of inventoryholders 30.

FIG. 6 illustrates in greater detail the components of a particularembodiment of inventory holder 30. In particular, FIG. 6 illustrates thestructure and contents of one side of an example inventory holder 30. Ina particular embodiment, inventory holder 30 may comprise any number offaces with similar or different structure. As illustrated, inventoryholder 30 includes a frame 310, a plurality of legs 328, and a dockingsurface 350.

Frame 310 holds inventory items 40. Frame 310 provides storage space forstoring inventory items 40 external or internal to frame 310. Thestorage space provided by frame 310 may be divided into a plurality ofinventory bins 320, each capable of holding inventory items 40.Inventory bins 320 may include any appropriate storage elements, such asbins, compartments, or hooks.

In a particular embodiment, frame 310 is composed of a plurality oftrays 322 stacked upon one another and attached to or stacked on a base318. In such an embodiment, inventory bins 320 may be formed by aplurality of adjustable dividers 324 that may be moved to resize one ormore inventory bins 320. In alternative embodiments, frame 310 mayrepresent a single inventory bin 320 that includes a single tray 322 andno adjustable dividers 324. Additionally, in particular embodiments,frame 310 may represent a load-bearing surface mounted on mobilityelement 330. Inventory items 40 may be stored on such an inventoryholder 30 by being placed on frame 310. In general, frame 310 mayinclude internal and/or external storage space divided into anyappropriate number of inventory bins 320 in any appropriate manner.

Additionally, in a particular embodiment, frame 310 may include aplurality of device openings 326 that allow mobile drive unit 20 toposition docking head 110 adjacent docking surface 350. The size, shape,and placement of device openings 326 may be determined based on thesize, the shape, and other characteristics of the particular embodimentof mobile drive unit 20 and/or inventory holder 30 utilized by inventorysystem 10. For example, in the illustrated embodiment, frame 310includes four legs 328 that form device openings 326 and allow mobiledrive unit 20 to position mobile drive unit 20 under frame 310 andadjacent to docking surface 350. The length of legs 328 may bedetermined based on a height of mobile drive unit 20.

Docking surface 350 comprises a portion of inventory holder 30 thatcouples to, abuts, and/or rests upon a portion of docking head 110, whenmobile drive unit 20 is docked to inventory holder 30. Additionally,docking surface 350 supports a portion or all of the weight of inventoryholder 30 while inventory holder 30 is docked with mobile drive unit 20.The composition, shape, and/or texture of docking surface 350 may bedesigned to facilitate maneuvering of inventory holder 30 by mobiledrive unit 20. For example, as noted above, in particular embodiments,docking surface 350 may comprise a high-friction portion. When mobiledrive unit 20 and inventory holder 30 are docked, frictional forcesinduced between docking head 110 and this high-friction portion mayallow mobile drive unit 20 to maneuver inventory holder 30.Additionally, in particular embodiments, docking surface 350 may includeappropriate components suitable to receive a portion of docking head110, couple inventory holder 30 to mobile drive unit 20, and/orfacilitate control of inventory holder 30 by mobile drive unit 20.

Holder identifier 360 marks a predetermined portion of inventory holder30 and mobile drive unit 20 may use holder identifier 360 to align withinventory holder 30 during docking and/or to determine the location ofinventory holder 30. More specifically, in particular embodiments,mobile drive unit 20 may be equipped with components, such as holdersensor 150, that can detect holder identifier 360 and determine itslocation relative to mobile drive unit 20. As a result, mobile driveunit 20 may be able to determine the location of inventory holder 30 asa whole. For example, in particular embodiments, holder identifier 360may represent a reflective marker that is positioned at a predeterminedlocation on inventory holder 30 and that holder sensor 150 can opticallydetect using an appropriately-configured camera.

Depending on the configuration and characteristics of mobile drive unit20 and inventory system 10, mobile drive unit 20 may move inventoryholder 30 using a variety of appropriate methods. In a particularembodiment, mobile drive unit 20 is capable of moving inventory holder30 along a two-dimensional grid, combining movement along straight-linesegments with ninety-degree rotations and arcing paths to transportinventory holder 30 from the first location to the second location.Additionally, while moving, mobile drive unit 20 may use fixed objectslocated in the workspace as reference points to assist in navigation.For example, in particular embodiments, inventory system 10 includesmultiple fiducial marks. Mobile drive unit 20 may be configured todetect fiducial marks and to determine the location of mobile drive unit20 and/or measure its movement based on the detection of fiducial marks.

After mobile drive unit 20 arrives at the second location, mobile driveunit 20 may perform appropriate operations to facilitate access toinventory items 40 stored in inventory holder 30. For example, mobiledrive unit 20 may rotate inventory holder 30 to present a particularface of inventory holder 30 to an operator of inventory system 10 orother suitable party, such as a packer selecting inventory items 40 frominventory holder 30. Mobile drive unit 20 may also undock from inventoryholder 30. Alternatively, instead of undocking at the second location,mobile drive unit 20 may transport inventory holder 30 back to the firstlocation or to a third location after any appropriate actions have beentaken involving inventory items 40. For example, after a packer hasremoved particular inventory items 40 from inventory holder 30, mobiledrive unit 20 may return inventory holder 30 to its original storagelocation, a new storage location, or another inventory station. Mobiledrive unit 20 may then undock from inventory holder 30 at this newlocation.

As described above, embodiments herein are directed to utilizing mobiledrive units to facilitate efficient operator handling of inventory itemsbeing processed through an inventory system. FIG. 7 is a process flowillustrating an example process 400 that can be performed in theinventory system 10 according to a particular embodiment. At 402 in theprocess 400, a truck or other delivery vehicle arrives at a workspace70. The truck may be carrying inventory items 40, which may be groupedinto receptacles for the transit process. These receptacles(hereinafter, “receipt receptacles”) may be cardboard boxes, plasticreusable containers, pallets, envelopes, or any other receptacle capableof containing single or multiple items. For example, the cases describedabove with respect to FIG. 1 are an example of receipt receptacles.

At 404, a “check-in operation” or touch is performed. Examples ofcheck-in stations 50C, 550C at which the check-in operation 404 can beperformed are described above with respect to FIG. 1 and below withrespect to FIGS. 8 and 9. In the check-in operation, the receiptreceptacles are moved from the delivery vehicle onto case shuttles 32.Case shuttles 32 may be any holder, including inventory holders 30configured to receive receipt receptacles. The receipt receptacles canbe loaded without any sortation of the receipt receptacles or theinventory items contained therein, such as by operators or byautomation. As an example, the check-in operation may involvetransferring the receipt receptacles by hand, conveyor, fork lift,robotic device, or other method onto case shuttles 32. As part of thecheck-in operation, identification information of a receipt receptacle,such as a serial number or other tracking identification can becorrelated with the case shuttle 32 onto which the receipt receptaclewas placed. The information can be correlated using bar scanners, radiofrequency identification, or other identification methods. Such acorrelation may be stored, such as in memory 91, and used to maintainlocation information about receipt receptacles in the system, so thatthe management module can locate receipt receptacles for futureoperations. The check-in operation 404 can also include a mobile driveunit 20 moving the case shuttle 32 loaded with receipt receptacles to anappropriate location within the workspace 70 of the inventory system 10,such as to a storage location, to a receiving station 50R and/or to apick station 50P.

At 406, a “make pickable” operation is performed. Examples of receivestations 50R, 550R at which the make pickable operation 406 can beperformed are described above with respect to FIG. 1 and below withrespect to FIG. 10. In a make-pickable operation 406, inventory items 40are transferred from case shuttles 32 to pickable inventory holders 34.A pickable inventory holder 34 can be any structure capable of storinginventory items 40 and/or inventory item receptacles so that individualinventory items 40 can be located and accessed for subsequentoperations, such as picking items 40 for fulfilling orders processed bythe inventory system 10. As one example, a pickable inventory holder 34can be an inventory holder 30 with bins or other storage elementsconfigured to hold inventory items 40 and/or receptacles of inventoryitems 40. To facilitate make-pickable operations 406, one or more caseshuttles 32 can be brought to a single location with one or morepickable inventory holders 34. The inventory items 40 can be transferredfrom the case shuttles 32 to the pickable inventory holders 34 byvarious methods. In one method, the inventory items 40 are removed fromthe receipt receptacles and placed into storage elements of the pickableinventory holder 34. In another method, an entire receipt receptacle ofknown inventory items 40 is removed from a case shuttle 32 and placedonto the pickable inventory holder 34. The inventory items 40 can bemoved from case shuttles 32 to pickable inventory holders 34 byoperators or by automation. The make pickable operation at 406 mayinclude moving the pickable inventory holder 34 via mobile drive unit 20to an appropriate location within the workspace 70, such as to a storagelocation and/or to a pick station 50P.

In some embodiments, a check-in operation 404 may render a make pickableoperation 406 unnecessary. For example, the structure and contents of areceipt receptacle may be such that the contents are immediatelypickable upon completion of the check-in operation 404. As a firstillustrative example, during the check-in operation 404, a pallet (i.e.,a particular type of receipt receptacle) carrying identical items may beloaded on an inventory holder 30, rendering all the identical itemslocatable and accessible for subsequent operations (i.e., such that thepallet-bearing inventory holder 30 is a pickable inventory holder 34).

At 408, a “pick-to-order” operation can be performed. Examples of pickstations 50P and/or pick-to-order stations 550P at which thepick-to-order operation 408 can be performed are described above withrespect to FIG. 1 and below with respect to FIG. 11. The pick-to-orderoperation can include one or more operators transferring items from abin or other receptacle on a pickable inventory holder 34 (or from areceipt receptacle on a case shuttle 32) into order receptacles tocompile orders of inventory items 40. The order receptacles can be anyappropriate receptacle of a type described with respect to a receiptreceptacle. To assemble an order before shipping, an operator picks oneor more inventory items 40 from one or more case shuttles 32 or pickableinventory holders 34 and puts the picked items into an order receptacle.Each filled order receptacle represents a single order. As part of thepick-to-order operation 408, an operator can load one or more orderreceptacles into available open spaces on order shuttles 36. Inembodiments, the order shuttles 36 can be inventory holders 30configured to receive and organize order receptacles, e.g., completedorder receptacles. After the order shuttle 36 has been loaded with orderreceptacles, the pick-to-order operation can include using a mobiledrive unit 20 to move an order shuttle 36 to an appropriate location inthe workspace 70, such as to a storage location and/or to a ship station50S.

At 410, a “ship operation” can be performed. Examples of ship stations50S, 550S at which the ship operation 410 can be performed are describedabove with respect to FIG. 1 and below with respect to FIG. 12. The shipoperation can include transferring order receptacles from order shuttles36 into a truck or other shipping vehicle via mechanical automationand/or via actions performed by one or more operators. The shipoperation at 410 can include using a mobile drive unit 520 to move anorder shuttle to an appropriate location in a workspace 70 after orderreceptacles have been removed from the order shuttle 36 such as to astorage location and/or back to a pick-to-order station 50P forsubsequent reloading with order receptacles.

At 412, a delivery vehicle with order receptacles can leave theworkspace 70 and carry the order receptacles to destinations associatedwith orders received by the inventory system 10.

Inventory items 40 may be characterized by the management module 15according to different states during the process 400. For example, theinventory items 40 may be grouped together into receipt receptaclesduring a portion 414 of the process 400, such as from a time of deliveryat 402 up through undergoing the make-pickable operation 406. In anotherportion 416 of the process 400, items may be organized on anitem-specific basis, such as in a bin or receptacle of a pickableinventory holder 34 (or a case shuttle 32), in which the inventory items40 may be accessed independently of receipt receptacles. In anotherportion 418 of the process 400, items may be organized according toorder receptacles, which may correspond to orders of multiple distinctinventory items processed by the inventory system 10. Sorting inventoryitems according to a receipt receptacle basis, an item specific basis,and/or an order receptacle basis can focus the process 400 and reduce anumber of operator touches that may be needed otherwise to processinventory items 40 in the inventory system 10. In some embodiments, theprocess 400 can facilitate additional opportunities for automatedsortation of inventory items 40, which may lead to additionalefficiencies of the inventory system 10.

FIG. 8 is a perspective view of an example check-in station 550Caccording to a particular embodiment. In some embodiments, the check-instation 550C may correspond to the check-in station 50C of FIG. 1 and/orfacilitate the check-in operation 404 of FIG. 7. The check-in station550C can receive one or more delivery vehicles, e.g., a truck 502. Atransfer mechanism, e.g., a conveyor 504, may be routed from the truck.Receipt receptacles 512 carrying inventory items 40 can be unloaded fromthe truck 502 by the conveyor 504. For example, a human or a machine(not shown) may load the receipt receptacles 512 on to the conveyor 504from within the truck 502. As receipt receptacles move along theconveyor 504, a first operator 506A may open the receipt receptacles 512and/or remove excess packaging into a trash receptacle 516. Additionaloperators (such as 506B, 506C and 506D) can transfer the receiptreceptacles 512 from the conveyor 504 into open spaces on case shuttles532 without any sortation of the receipt receptacles 512 or theinventory items contained therein. For example, operators 506B, 506C,506D can transfer the receipt receptacles 512 into any open spaces onany available case shuttles 532 without any specific direction regardingsuch transfer. An identity of a receipt receptacle 512 can be determinedand correlated with a position on a case shuttle 532 in which thereceipt receptacle 512 is stored. In one illustrative example, anoperator 506 may scan a barcode on a receipt receptacle 512 and scan abarcode on the case shuttle 532. In another example, a camera or otheroptical device may determine an identity of a receipt receptacle 512and/or a corresponding storage position on a case shuttle 532 withoutintervention by the operator 506.

In some embodiments, the check-in station 550C is readily scalable toaccommodate a different size or speed of a check-in operation. Forexample, additional operators 506 and/or case shuttles 532 can be addedand/or removed from the check-in station 550C. In some aspects, theconveyor 504 can be extended to an adjacent check-in station 550C (notshown) in order to utilize operators and/or case shuttles 532 at bothstations for a single check-in operation from a particular vehicle 502.

In some embodiments, a particular operator 506D can store a receiptreceptacle 512 in any of the case shuttles 532 at the station 550C inwhich there is room for the receipt receptacle 512. In this manner,operators 506 may interact in a one-to-many or many-to-many relationshipwith the case shuttles 532. In some embodiments, in response toidentification of a receipt receptacle 512 (such as through a bar codescan), the management module 15 can communicate to an operator 506 toplace the identified receipt receptacle on a particular case shuttle 532(such as by a message on a display, an activated indicator light, or alaser pointer aimed at a place on the case shuttle 532). Such anarrangement may allow incoming receipt receptacles 512 to bepreliminarily sorted according to a plan of the management module 15,such as grouping together receipt receptacles 512 with unknown contentsfor later collective processing and/or distributing receipt receptacles512 with known contents according to other useful groupings for laterprocessing.

In some aspects, multiple features of the management module 15 canoperate independently at the check-in station 550C. For example, eachindividual operator 506 may be associated with an individual modulededicated to identifying storage positions on a case shuttle 532 wherethe operator 506 is storing receipt receptacles 512. Such a module forone operator 506 a may function independently of such a module foranother operator 506 b. In some aspects, the management module 15 has amodule configured to determine how full a case shuttle 532 is and/orwhen to move a case shuttle 532 with a mobile drive unit 520. The modulefocused on the fullness of the case shuttle 532 may functionindependently of any of the modules focused on identifying storagepositions of receptacles 512 on the case shuttles 532.

In some aspects, when a case shuttle 532 is ready to be carried away bya mobile drive unit 520, an operator 506 can be notified, such as by asound from a speaker, an activated light, a message on a display, or amobile drive unit 520 lifting the case shuttle 532. An instruction tothe mobile drive unit 520 to remove the ready case shuttle 532 may bedelayed until an operator authorizes the case shuttle 532 to be removed,such as by pressing a button on a touchscreen display or providing someother form of input.

In some embodiments, the check-in station 550C permits receiptreceptacles 512 to be checked into the inventory system 10 without ahuman operator 506 sorting the contents of the receipt receptacle 512.Check in without operator sortation may permit sortation by themanagement module 15. For example, the management module 15 maydetermine a location in the workspace 70 to store a case shuttle 532based on the receipt receptacles 512 carried by the case shuttle 532.For example, the management module may instruct a mobile drive unit 20to move a case shuttle 532 to a particular floor (e.g., W, X, Y, or Z inFIG. 1) based on factors such as inventory items 40 known to be inreceipt receptacles 512 carried by the case shuttle 532, inventory itemsknown to be on the floor (e.g., X), inventory items 40 known to be on adifferent floor (e.g., W, Y, or Z), and/or stations 50 on the particularfloor that are capable of processing inventory items 40 stored in thereceipt receptacles 512. As illustrative examples, the management module15 may send a first case shuttle 532 with receipt receptacles 512 havingknown inventory items 40 to a floor with a low supply of those inventoryitems 40, and send a case shuttle 532 with receipt receptacles 512 ofunknown contents to a floor with a station having capacity to processunknown contents. In another illustrative example, the management modulemay distribute case shuttles 532 with receipt receptacles 512 of unknowncontents across multiple floors, which may allow the unknown contents tobe more quickly processed for utilization in the inventory system 10. Insome embodiments, a check-in process without operator sortation mayreduce an amount of time between an arrival of inventory items 40 to theinventory system 10 or workspace 70 and a confirmation that the arrivingitems 40 are available for subsequent operations in the inventory system10, thereby increasing the responsiveness of the inventory system 10 asa whole.

FIG. 9 illustrates another example of a check-in station 550C accordingto a particular embodiment. In some embodiments, the check-in station550C may correspond to the check-in station 50C of FIG. 1 and/or be usedin addition or as an alternative to the check-in station 550C of FIG. 8.In some embodiments, a shipment of receipt receptacles 512 arriving atthe workspace 70 may include only receipt receptacles 512 with knowncontents. For example, the receipt receptacles 512 may have clearlabeling identifying the contents and/or may already be indexed inmemory 91 of the inventory system 10, such as if arriving from a relatedinventory system 10. At the check-in station 550C, the receiptreceptacles 512 with known contents can be transferred directly topickable inventory holders 534. For example, the pickable inventoryholders 534 may be inventory holders 30 configured to hold the knownreceipt receptacles 512. The identity of a known receipt receptacle 512and associated storage position on the pickable inventory holder 534 canbe identified and correlated by the management module 15. Similar to thecheck in operation described with respect to FIG. 8, the receiptreceptacles 512 with known contents of FIG. 9 may be transferred,without any sortation of the receipt receptacles 512 or the inventoryitems contained therein, to any open spaces on any available pickableinventory holders 534 without any specific direction regarding suchtransfer. Thus, the check-in station 550C may function to simultaneouslyperform the check-in operation 404 and the make-pickable operation 406of FIG. 7 for groups of receipt receptacles 512 with known contents.

FIG. 10 is a perspective view of an example of a receiving station 550Rin accordance with a particular embodiment. For example, the station550R may correspond to a station 50R of FIG. 1 and/or perform themake-pickable operation 406 of FIG. 7. A receipt receptacle 512 on acase shuttle 532 can be identified for an operator 506 to remove. Theoperator 506 can remove the receipt receptacle 512 from the case shuttle532 and place the items 40 from the receipt receptacle into a pickableinventory holder 534. Items 40 stowed in the pickable inventory holder534 are pickable for subsequent operations. The operator may stow allitems 40 from a single receipt receptacle 512 into a single or multiplebins of a single or multiple pickable inventory holders 534. Forexample, mobile drive units 520 may bring and take pickable inventoryholders 534 to and from the receive station 550R until a receiptreceptacle 512 is emptied of items 40. The empty receipt receptacle 512may be discarded in a trash receptacle 516 and/or otherwiseappropriately disposed of.

In some aspects, an entire receipt receptacle 512 can be placed into apickable inventory holder 534, and items 40 in the receipt receptacle512 can be individually picked during subsequent operations. Forexample, transferring a receipt receptacle 512 with multiple items 40 ofthe same type into a pickable inventory holder 534 may be more efficientthan individually loading the multiple items into the pickable inventoryholder 534. A receipt receptacle 512 returning to the receiving station550R after being emptied of items 40 by pick operations may be removedand disposed of, such as in the trash receptacle 516. In some aspects, areceipt receptacle 512 that is not entirely emptied can be removed fromthe pickable inventory holder 534 upon reaching a certain threshold ofremaining items, and the remaining items 40 can be distributed into openspaces in pickable inventory holders 534. Removing a near empty receiptreceptacle 512 may increase storage density by making room available ona pickable inventory holder for another receipt receptacle 512 with agreater number of items.

The trash receptacle 516 may be shared between different stations. Insome embodiments, the stations may be on different floors. For example,one receiving station 550R on a first level may include a trash chute tomove trash to a trash receptacle 516 of a check-in station 550C oranother receiving station 550R on another level. In some embodimentstrash receptacles 516 may be moved between floors, such as to reach atrash dumper in communication with the outside of the building.

In some embodiments, the receive station 550R includes a cart 538 orother working surface upon which the operator 506 can place a receptacle512 for unloading items 40 out of the receipt receptacle 512. In someembodiments, an operator 506 may pull multiple receipt receptacles 512from one or more case shuttles 532 before unloading items 40 from thereceipt receptacles 512 into the pickable inventory holders 534. Forexample, mobile drive units 520 may bring a series of case shuttles 532having specific receipt receptacles 512 to be pulled by the operator506.

Use of case shuttles 532 at the receiving station 550R can facilitate anumber of other features. For example, receipt receptacles 512 carriedby the case shuttles 532 can be processed at the receive station 550R ina different order than an order in which the receipt receptacles 512were checked in, such as at a station 550C and/or at operation 404 ofFIG. 7. In one illustrative example, if an ordered inventory item 40 isknown to be in a particular receipt receptacle 512, a case shuttle 532may be advanced out of sequence in order to make the item 40 pickableand expedite the process of moving the item 40 through the inventorysystem 10. In a similar example, a case shuttle 532 may be advanced outof sequence to make an item 40 pickable based on a popularity of theitem 40, such as if the item is frequently ordered though no outstandingorders for the item 40 are pending. Conversely, if an inventory item 40is not requested as part of a current order or is not likely to beordered or requested in the near future, the make pickable operation 406for the case shuttle 532 containing the receipt receptacle 512 with theparticular inventory item 40 may be delayed until the particularinventory item 40 is ordered or otherwise requested, therebyfacilitating efficient processing of current or likely future orders orrequests for items. In another illustrative example, the managementmodule can select case shuttles 532 to bring to a receive station 550Rand/or receipt receptacles 512 to be removed at the receive station 550Rbased on a size of inventory items 40 in the receipt receptacles 512.For example, the management module 15 may prompt an operator 506 toprocess a series of receipt receptacles 512 having items 40 of a similarsize, which may reduce a number of pickable inventory holders 534 withdifferent sized bins, openings, or other receptacles needed to store thestowed items 40. In another example, case shuttles 532 are brought to areceive station 550R based on a speed at which an operator 506 of thereceive station 550R is stowing items from receipt receptacles 512 intopickable inventory holders 534. For example, a management module 15 mayprompt a mobile drive unit 520 to bring another case shuttle 532 to areceive station 550R just before an operator 506 runs out of items thathe is stowing from another receipt receptacle 512. In yet anotherexample, a sequence of receipt receptacles 512 brought to the receivestation 550R by case shuttles 532 can be determined based on a length oftime that the receipt receptacle 512 has been checked in. For example, amanagement module may prioritize receipt receptacles that are older orhave been checked in for a longer period of time. In some aspects, thesequence determination may also be determined based on distance of acase shuttle 532 to a receive station 550R. In some aspects, receiptreceptacles 512 with unknown contents are prioritized. For example,prioritizing unknown inventory may reduce an amount of time thatinventory items 40 may be present in the inventory system 10 withoutbeing operable in the inventory system 10. In some aspects, receiptreceptacles 512 with items 40 that need special preparation areprioritized. For example, fragile items 40 that are to speciallypackaged, items 40 that are to be giftwrapped, and/or items 40 that areto receive specialized labeling may be directed to a station having thesupplies for such actions. In some embodiments, a tiered prioritizationmay be implemented. For example, the management module 15 may prioritizecase shuttles 532 containing known inventory items 40 that are thesubject of existing orders over case shuttles 532 containing unknowninventory items 40, and prioritize unknown inventory items over knowninventory items 40 that are not yet the subject of existing orders.

In embodiments, the management module 15 may assign a receipt receptacle512 (and/or a case shuttle 532 bearing the receipt receptacle) to aparticular floor (e.g., W, X, Y, or Z) based on information about thefloor and/or information about the receipt receptacle 512. For example,a case shuttle 532 may be assigned to a particular floor based on thatfloor being preferred for fulfilling orders for items contained in areceipt receptacle 512 on the case shuttle 532. As another example, areceipt receptacle 512 may be assigned to a particular floor based onitems in the receipt receptacle 512 being frequently requested inconjunction with other items on the floor. As an illustrative example, areceipt receptacle 512 with ajar of peanut butter may be assigned to afloor that has a jar of jelly stored in a pickable inventory holder 534or in a case shuttle 532. As a further example, a receipt receptacle 512may be assigned to a particular floor based on items in the receiptreceptacle 512 being of a size that can be accommodated in appropriatelysized storage space on that floor. In yet another example, a receiptreceptacle 512 may be assigned to a particular floor to improve alikelihood that a sufficient amount of receipt receptacles 512 areavailable on that floor to occupy operators 506 tasked with processingreceipt receptacles. In an additional example, a receipt receptacle 512may be assigned to a particular floor to improve a balance of itemsacross the floors, such as if the receipt receptacle 512 contains anitem that is more prevalent on other floors than on the assigned floor.

FIG. 11 is a perspective view of an example of a pick-to-order station550P in accordance with a particular embodiment. For example, thepick-to-order station 550P can correspond to a pick station 50P of FIG.1 and/or facilitate the pick-to-order operation at 408 in FIG. 7. Thepick-to-order station 550P can facilitate transfer of pickable items 40into order receptacles 514. The pick-to-order station 550P can includemultiple operators 506A, 506B, 506C to facilitate the pick-to-orderoperation. The operators 506A, 506B, 506C can be organized on eitherside of a partition 546, which may be a wall or any other structurecapable of dividing or separating adjacent spaces. Although FIG. 11shows three operators 506A, 506B, and 506C organized on either side of apartition 546, any suitable number of operators can be used. In someembodiments, the number of operators on a first side of the partition546 (e.g., on the side depicted toward the right of FIG. 11) isdetermined based on a speed at which one or more operators on a second,opposite side of the partition can complete tasks.

Any operator 506A, 506C on the first side of the partition can prepareorder receptacles 514. For example, an order receptacle 514 may beprepared based on a number and/or size of items 40 in an order, such aspreparing padded envelopes for small single items and/or preparinglarger boxes for larger and/or multiple items. The order receptacles 514can be placed into openings, compartments, or positions in the partition546. An operator 506B on an opposite side of the partition can removepickable items 40 from a pickable inventory holder 534 and place eachitem 40 in an order receptacle designated for the item 40. For example,the management module may indicate an item 40 to be taken from thepickable inventory holder 534 and an order receptacle 514 in which theitem is to be placed. Any operator 506A, 506C on the first side of thepartition may be instructed by the management module to remove orderreceptacles 514 from the partition when the order receptacle 514includes all of the items of an order. Any operator 506A, 506C on thefirst side of the partition may perform appropriate actions fortransforming the order receptacle 514 with all items of an order into acompleted order receptacle 514, e.g., so that the order receptacle 514is ready for shipment or other transfer out of the workspace 70. Suchactions may include adding dunnage or other appropriate packingmaterials to the order receptacle 514, adding packing slips to the orderreceptacle 514, taping or otherwise sealing the order receptacle 514,weighing the order receptacle 514, and/or adding labels (e.g., shippinglabels, which may reflect a weight obtained by weighing the orderreceptacle 514) to the order receptacle 514. An order receptacle 514including all of the items of an order (e.g., a completed orderreceptacle 514) can be placed on an order shuttle 536, such as by anoperator 506A, 506C on a first side of the partition at the instructionof the management module 15. For example, the order shuttle 536 mayinclude different spaces 548 corresponding to different groups ofdestinations for the orders. The coordinated actions of the operators506A-506C at the pick-to-order station 550P enable picking of items byone operator directly into order receptacles prepared and completed byat least one other operator, thereby eliminating any additionalconveyance, transfer and/or touches and additional intermediateoperations and/or stations to create completed order receptacles.

In some embodiments, the management module 15 provides instructions fordirecting activity of the operators 506A, 506B on the first side of thepartition. For example, the management module 15 can instruct anoperator 506 a to assemble and/or otherwise prepare an order receptacle514 for items 40 of a specific order. The management module 15 caninstruct that the prepared order receptacle 514 be placed at aparticular opening, compartment, or position within the partition 546.For example, the management module 15 may select a particular opening,compartment, or position for an order receptacle 514 based on factorssuch as a priority of the order, a size of the opening, compartment, orposition relative to a size of the receipt receptacle 514, time costsfor an operator 506A on a first side of the partition to travel to theparticular opening, compartment, or position to load the receptacle 514into the partition (e.g., including any time losses from navigatingaround another operator 506C interacting with the same side of thepartition 546), time costs for an operator 506B on the opposite side ofthe partition 546 to travel to the particular opening, compartment, orposition to place an ordered item 40 in the order receptacle 514 (e.g.,distance from a pickable inventory holder 534 to the particular opening,compartment, or position), and/or time costs for an operator 506A or506C on a first side of the partition to travel to the particularopening, compartment, or position to remove the order receptacle whenall items 40 of the order have been loaded into the order receptacle.

In some embodiments, the management module 15 can provide instructionsthat determine timing and/or sequencing of activity of the operators506A, 506C on the first side of the partition. The management module 15can provide instructions so that actions relating to a high priorityreceipt receptacle 514 happen before actions relating to a lowerpriority receipt receptacle 514. As one example, the management module15 may prioritize actions of removing a receipt receptacle 514designated for an order shuttle 536 that is at the pick-to-order station550P ahead of removing a receipt receptacle 514 for an order shuttle 536that has not yet arrived to the pick-to-order station 550P. As a furtherexample, the management module 15 can provide instructions to prioritizeremoving a specific receipt receptacle 514 before or after adding adifferent receipt receptacle into the partition 546. In an illustrativeexample, adding a new receipt receptacle 514 designated to receive anitem 40 from a pickable inventory holder 534 that is at or approachingthe pick-to-order station 550P may be prioritized before removing areceipt receptacle 514 for an order designated for an order shuttle 536at the pick-to-order station 550P. In another illustrative example,removing a receipt receptacle 514 designated for a particular ordershuttle 536 already at the pick-to-order station 550P may be prioritizedbefore adding a new receipt receptacle 514 for an order designated foran order shuttle 536 that has not yet arrived to the pick-to-orderstation 550P. Actions may be prioritized based on the effect of theactions on completing order shuttles 536 and/or on processing items 40from pickable inventory holders 534.

In some embodiments, the pick-to-order station 550P can also utilizealternate order shuttles 536′. For example, the alternate order shuttles536′ may be configured for containing alternate order receptacles 514′.

In some embodiments, the alternate order receptacles 514′ may includeorder receptacles bound for another level (e.g., W, X, Y, or Z) of theinventory system 10 and/or another inventory system 10. The secondoperator 506B can be instructed to move items 40 from the pickableinventory holder 534 to alternate order receptacles 514′ on thealternate order shuttles 536′. In some aspects, the alternate orderreceptacles 514 may become the receive receptacles 512 with knowncontents for another inventory system 10.

In some embodiments, the alternate order shuttles 536′ may be assignedto a particular floor of the inventory system for moving inventory itemsto a particular floor from the floor on which the pick-to-order station550P is situated. In an illustrative example, an alternate orderreceptacle 514′ is provided for each of the other levels (e.g., W, X,and Y if the pick-to-order station 550R is on level Z) and is moved orcarried to that other level by a mobile drive unit 520 when thealternate order receptacle 514′ reaches a threshold capacity of items 40and/or when a mobile drive unit 520 bound for that level reaches thealternate order receptacle 514′. In some aspects, a filled alternateorder receptacle 514′ may be transferred to an alternate order shuttle536′ brought to the station by a mobile drive unit 520 en route toanother floor. In some aspects, a mobile drive unit 520 may pick up analternate order shuttle 536′ bearing an alternate order receptacle 514′and take the combination to another floor.

In some embodiments, the management module may determine a pick-to-orderstation 50P on one of the floors (e.g., W, X, Y, or Z) to fulfill anorder from items 40 distributed across multiple floors. The managementmodule 15 may determine which floor has the greatest number of inventoryitems for the order. For example, the management system may assign anorder to a floor that has four out of five inventory items for an orderrather than a floor that only has three out of five inventory items foran order. A management module 15 may create one or more inter-floororders to move the missing inventory items to the selected floor. Themanagement module 15 may instruct a shuttle to delay moving to anotherfloor until the shuttle is filled with items for that other floor. Theitem 40 transferred between floors may be picked from the shuttle by theoperator 506B and combined with other items picked from shuttles on thefloor into order receptacles.

In some aspects, distribution of products provided by storing caseshuttles 532 on a particular floor can reduce an amount of inter-floortransfers that are needed to complete orders. In some embodiments,inter-floor transfers can also be performed to balance distribution ofinventory across multiple floors instead of, or in addition to,inter-floor transfers for fulfilling an order. As an illustrativeexample, an inter-floor transfer from floor Z to floor X in FIG. 1 mayinclude a red t-shirt needed to complete an order at the pick station50P on floor X. Three of six total blue t-shirts stored on floor Z maybe sent in the inter-floor transfer with the red t-shirt so that thepick stations 50P on floor X and floor Z will equally be able to handleany future orders for a blue t-shirt without conducting extrainter-floor transfers. In some aspects, an inter-floor transfer mayinclude moving an entire shuttle in order to get an item on thatshuttle. In some aspects, the inter-floor transfer involves transferringa desired item from one shuttle to a collecting shuttle to move to theother floor with other collected items from the source floor.

FIG. 12 illustrates a perspective view of an example of a ship station550S in accordance with a particular embodiment. In some embodiments,the ship station 550S may correspond to a ship station 50S of FIG. 1and/or facilitate the ship operation 410 of FIG. 7. Order shuttles 536bearing order receptacles 514 can be sent to the ship station 550S usingmobile drive units 20. Operators 506 can be instructed as to whichspaces 548 are to be emptied at the ship station 550S (e.g., thatcorrespond to a particular truck). In some embodiments, large orderreceptacles 514 can be placed on a conveyor 504 and small orderreceptacles 514 can be consolidated into shipping receptacles 552 fortransfer onto a truck or other delivery vehicle. In some embodiments, anorder shuttle 536 can be moved away from the shipping station 550S whena space 548 corresponding to a truck at the station 550S is emptied. Theorder shuttle 536 can be stored until a truck for order receptacles 514of another space 548 of the order shuttle 536 has arrived to the same ora different shipping station 550S. Such an arrangement may permit anyfinished order to be accessed upon a specific triggering event, such asthe arrival of a transportation vehicle for conveying the orderreceptacle 514 to its ultimate destination.

FIG. 13 illustrates aspects of an example environment 1300 forimplementing aspects in accordance with various embodiments. As will beappreciated, although a Web-based environment is used for purposes ofexplanation, different environments may be used, as appropriate, toimplement various embodiments. The environment includes an electronicclient device 1302, which can include any appropriate device operable tosend and receive requests, messages, or information over an appropriatenetwork 1304 and convey information back to a user of the device.Examples of such client devices include personal computers, cell phones,handheld messaging devices, laptop computers, set-top boxes, personaldata assistants, electronic book readers, and the like. The network caninclude any appropriate network, including an intranet, the Internet, acellular network, a local area network or any other such network orcombination thereof. Components used for such a system can depend atleast in part upon the type of network and/or environment selected.Protocols and components for communicating via such a network are wellknown and will not be discussed herein in detail. Communication over thenetwork can be enabled by wired or wireless connections and combinationsthereof. In this example, the network includes the Internet, as theenvironment includes a Web server 1306 for receiving requests andserving content in response thereto, although for other networks analternative device serving a similar purpose could be used as would beapparent to one of ordinary skill in the art.

The illustrative environment includes at least one application server1308 and a data store 1310. It should be understood that there can beseveral application servers, layers, or other elements, processes orcomponents, which may be chained or otherwise configured, which caninteract to perform tasks such as obtaining data from an appropriatedata store. As used herein the term “data store” refers to any device orcombination of devices capable of storing, accessing, and retrievingdata, which may include any combination and number of data servers,databases, data storage devices and data storage media, in any standard,distributed or clustered environment. The application server can includeany appropriate hardware and software for integrating with the datastore as needed to execute aspects of one or more applications for theclient device, handling a majority of the data access and business logicfor an application. The application server provides access controlservices in cooperation with the data store and is able to generatecontent such as text, graphics, audio and/or video to be transferred tothe user, which may be served to the user by the Web server in the formof HyperText Markup Language (“HTML”), Extensible Markup Language(“XML”) or another appropriate structured language in this example. Thehandling of all requests and responses, as well as the delivery ofcontent between the client device 1302 and the application server 1308,can be handled by the Web server. It should be understood that the Weband application servers are not required and are merely examplecomponents, as structured code discussed herein can be executed on anyappropriate device or host machine as discussed elsewhere herein.

The data store 1310 can include several separate data tables, databasesor other data storage mechanisms and media for storing data relating toa particular aspect. For example, the data store illustrated includesmechanisms for storing information which can be used by modulesdescribed herein, such as resource scheduling information 1312, routeplanning information 1314, segment reservation information 1316, and/orinventory information 1318. It should be understood that there can bemany other aspects that may need to be stored in the data store, such asfor page image information and to access right information, which can bestored in any of the above listed mechanisms as appropriate or inadditional mechanisms in the data store 1310. The data store 1310 isoperable, through logic associated therewith, to receive instructionsfrom the application server 1308 and obtain, update or otherwise processdata in response thereto.

Each server typically will include an operating system that providesexecutable program instructions for the general administration andoperation of that server and typically will include a computer-readablestorage medium (e.g., a hard disk, random access memory, read onlymemory, etc.) storing instructions that, when executed by a processor ofthe server, allow the server to perform its intended functions. Suitableimplementations for the operating system and general functionality ofthe servers are known or commercially available and are readilyimplemented by persons having ordinary skill in the art, particularly inlight of the disclosure herein.

The environment in one embodiment is a distributed computing environmentutilizing several computer systems and components that areinterconnected via communication links, using one or more computernetworks or direct connections. However, it will be appreciated by thoseof ordinary skill in the art that such a system could operate equallywell in a system having fewer or a greater number of components than areillustrated in FIG. 13. Thus, the depiction of the system 1300 in FIG.13 should be taken as being illustrative in nature and not limiting tothe scope of the disclosure.

The various embodiments further can be implemented in a wide variety ofoperating environments, which in some cases can include one or more usercomputers, computing devices or processing devices which can be used tooperate any of a number of applications. User or client devices caninclude any of a number of general purpose personal computers, such asdesktop or laptop computers running a standard operating system, as wellas cellular, wireless and handheld devices running mobile software andcapable of supporting a number of networking and messaging protocols.Such a system also can include a number of workstations running any of avariety of commercially-available operating systems and other knownapplications for purposes such as development and database management.These devices also can include other electronic devices, such as dummyterminals, thin-clients, gaming systems and other devices capable ofcommunicating via a network.

Most embodiments utilize at least one network that would be familiar tothose skilled in the art for supporting communications using any of avariety of commercially-available protocols, such as TransmissionControl Protocol/Internet Protocol (“TCP/IP”), Open SystemInterconnection (“OSI”), File Transfer Protocol (“FTP”), Universal Plugand Play (“UpnP”), Network File System (“NFS”), Common Internet FileSystem (“CIFS”) and AppleTalk. The network can be, for example, a localarea network, a wide-area network, a virtual private network, theInternet, an intranet, an extranet, a public switched telephone network,an infrared network, a wireless network, and/or any combination thereof.

In embodiments utilizing a Web server, the Web server can run any of avariety of server or mid-tier applications, including Hypertext TransferProtocol (“HTTP”) servers, FTP servers, Common Gateway Interface (“CGP”)servers, data servers, Java servers and business application servers.The server(s) also may be capable of executing programs or scripts inresponse requests from user devices, such as by executing one or moreWeb applications that may be implemented as one or more scripts orprograms written in any programming language, such as Java®, C, C# orC++, or any scripting language, such as Perl, Python or TCL, as well ascombinations thereof. The server(s) may also include database servers,including without limitation those commercially available from Oracle®,Microsoft®, Sybase®, and IBM®.

The environment can include a variety of data stores and other memoryand storage media as discussed above. These can reside in a variety oflocations, such as on a storage medium local to (and/or resident in) oneor more of the computers or remote from any or all of the computersacross the network. In a particular set of embodiments, the informationmay reside in a storage-area network (“SAN”) familiar to those skilledin the art. Similarly, any necessary files for performing the functionsattributed to the computers, servers or other network devices may bestored locally and/or remotely, as appropriate. Where a system includescomputerized devices, each such device can include hardware elementsthat may be electrically coupled via a bus, the elements including, forexample, at least one central processing unit (“CPU”), at least oneinput device (e.g., a mouse, keyboard, controller, touch screen orkeypad) and at least one output device (e.g., a display device, printeror speaker). Such a system may also include one or more storage devices,such as disk drives, optical storage devices and solid-state storagedevices such as random access memory (“RAM”) or read-only memory(“ROM”), as well as removable media devices, memory cards, flash cards,etc.

Such devices also can include a computer-readable storage media reader,a communications device (e.g., a modem, a network card (wireless orwired), an infrared communication device, etc.) and working memory asdescribed above. The computer-readable storage media reader can beconnected with, or configured to receive, a computer-readable storagemedium, representing remote, local, fixed, and/or removable storagedevices as well as storage media for temporarily and/or more permanentlycontaining, storing, transmitting, and retrieving computer-readableinformation. The system and various devices also typically will includea number of software applications, modules, services or other elementslocated within at least one working memory device, including anoperating system and application programs, such as a client applicationor Web browser. It should be appreciated that alternate embodiments mayhave numerous variations from that described above. For example,customized hardware might also be used and/or particular elements mightbe implemented in hardware, software (including portable software, suchas applets) or both. Further, connection to other computing devices suchas network input/output devices may be employed.

Storage media and computer readable media for containing code, orportions of code, can include any appropriate media known or used in theart, including storage media and communication media, such as but notlimited to volatile and non-volatile, removable and non-removable mediaimplemented in any method or technology for storage and/or transmissionof information such as computer readable instructions, data structures,program modules or other data, including RAM, ROM, Electrically ErasableProgrammable Read-Only Memory (“EEPROM”), flash memory or other memorytechnology, Compact Disc Read-Only Memory (“CD-ROM”), digital versatiledisk (DVD) or other optical storage, magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices or any othermedium which can be used to store the desired information and which canbe accessed by the a system device. Based at least in part on thedisclosure and teachings provided herein, a person of ordinary skill inthe art will appreciate other ways and/or methods to implement thevarious embodiments.

The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. It will, however, beevident that various modifications and changes may be made thereuntowithout departing from the broader spirit and scope of the disclosure asset forth in the claims.

Other variations are within the spirit of the present disclosure. Thus,while the disclosed techniques are susceptible to various modificationsand alternative constructions, certain illustrated embodiments thereofare shown in the drawings and have been described above in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructionsand equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosed embodiments (especially in thecontext of the following claims) are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. The term“connected” is to be construed as partly or wholly contained within,attached to, or joined together, even if there is something intervening.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate embodiments of the invention anddoes not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this disclosure are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications and patents,cited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

What is claimed is:
 1. An inventory management system, comprising: aplurality of mobile drive units configured to traverse a plurality offloors, the plurality of floors disposed vertically relative to eachother, each floor comprising a plurality of inventory items and a pickstation, and each floor configured to operate substantiallyindependently of other floors; and a management module configured to:assign an order for a set of inventory items to one of the plurality offloors based at least in part on a relative match between the pluralityof inventory items of each floor and the set of inventory items of theorder; identify an item from the set of inventory items that is notavailable on the assigned floor but is available on another floor; andinstruct a mobile drive unit to move the item to the assigned floor fromthe other floor to be picked at the pick station on the assigned floor.2. The inventory system of claim 1, wherein the management module isfurther configured to instruct the mobile drive unit to move areceptacle having items for multiple orders assigned to the assignedfloor and move the receptacle from the other floor to the assigned floorfor the multiple orders.
 3. The inventory system of claim 1, wherein themanagement module being configured to instruct a mobile drive unit tomove the item to the assigned floor from the other floor to be picked atthe pick station on the assigned floor comprises the management modulebeing configured to instruct the mobile drive unit to dock with ashuttle containing the item.
 4. The inventory system of claim 3, whereinthe management module is further configured to instruct a mobile driveunit to drop off the shuttle at a pick station of the other floor forreceiving the item to be moved to the assigned floor.
 5. The inventorysystem of claim 1, wherein the management module being configured toinstruct a mobile drive unit to move the item to the assigned floor fromthe other floor to be picked at the pick station on the assigned floorcomprises the management module being configured to instruct the mobiledrive unit to transport a shuttle to a location for transfer of the itemto the shuttle and to the assigned floor.
 6. The inventory system ofclaim 1, further comprising a check-in station configured to receivereceipt receptacles of inventory items for each of the plurality offloors.
 7. The inventory system of claim 1, further comprising a shipstation configured to receive order receptacles of inventory items fromeach of the plurality of floors.
 8. The inventory system of claim 1,further comprising: a check-in station configured to receive receiptreceptacles of inventory items for each of the plurality of floors; anda ship station configured to receive order receptacles of inventoryitems from each of the plurality of floors.
 9. A method comprising,under the control of one or more computer systems configured withexecutable instructions: assigning an order for a set of inventory itemsto one of a plurality of floors, the plurality of floors disposedvertically relative to each other, each floor comprising a plurality ofinventory items and a pick station, and each floor configured to operatesubstantially independently of other floors, wherein the order isassigned based at least in part on a relative match between theplurality of inventory items of each floor and the set of inventoryitems of the order; identifying an item from the set of inventory itemsthat is not available on the assigned floor but is available on anotherfloor; and instructing a mobile drive unit to move the item to theassigned floor from the other floor to be picked at the pick station onthe assigned floor.
 10. The method of claim 9, further comprisinginstructing the mobile drive unit to move a receptacle having items formultiple orders assigned to the assigned floor and move the receptaclefrom the other floor to the assigned floor for the multiple orders. 11.The method of claim 9, wherein the instructing the mobile drive unit tomove the item to the assigned floor from the other floor to be picked atthe pick station on the assigned floor comprises instructing the mobiledrive unit to dock with a shuttle containing the item.
 12. The method ofclaim 11, further comprising instructing the mobile drive unit to dropoff the shuttle at a pick station of the other floor for receiving theitem to be moved to the assigned floor.
 13. The method of claim 9,wherein the instructing the mobile drive unit to move the item to theassigned floor from the other floor to be picked at the pick station onthe assigned floor comprises instructing the mobile drive unit totransport a shuttle to a location for transfer of the item to theshuttle and to the assigned floor.
 14. The method of claim 9, whereinthe plurality of floors is associated with at least one of: a check-instation configured to receive receipt receptacles of inventory items foreach of the plurality of floors; or a ship station configured to receiveorder receptacles of inventory items from each of the plurality offloors.
 15. A non-transitory computer-readable medium havingcomputer-executable instructions stored thereon, wherein theinstructions, when executed, cause a computer system having at least onecomputer processor to perform a method comprising: instructing movementof a plurality of receipt receptacles from a shipping vehicle to aplurality of case shuttles without separating or sorting inventory itemscontained in the receipt receptacles; for each receipt receptacle of theplurality of receipt receptacles, obtaining information regardinginventory items contained in the receipt receptacle; assigning aparticular receipt receptacle to a floor of an inventory system based atleast in part on information about the floor of the inventory system andthe obtained information regarding inventory items contained in theparticular receipt receptacle, the inventory system comprising aplurality of floors disposed vertically relative to each other, and eachfloor configured to operate substantially independently of other floors;and instructing movement of the case shuttle bearing the particularreceipt receptacle to a storage location on the floor to which theparticular receipt receptacle is assigned.
 16. The non-transitorycomputer-readable medium of claim 15, wherein the method furthercomprises: receiving an order requesting at least one inventory item;and determining a preferred floor for the fulfilling the order; whereinassigning a particular receipt receptacle to a floor of an inventorysystem based at least in part on information about the floor and theobtained information regarding inventory items contained in theparticular receipt receptacle comprises assigning the particular receiptreceptacle to the preferred floor based at least in part on a presence,in the particular receipt receptacle, of at least one inventory itemrequested in the order associated with the preferred floor.
 17. Thenon-transitory computer-readable medium of claim 15, wherein the methodfurther comprises: determining that a particular floor has less of acertain type of item than other floors; and wherein assigning aparticular receipt receptacle to a floor of an inventory system based atleast in part on information about the floor and the obtainedinformation regarding inventory items contained in the particularreceipt receptacle comprises assigning the particular receipt receptacleto the particular floor based at least in part on a presence, in theparticular receipt receptacle, of an inventory item of the certain type.18. The non-transitory computer-readable medium of claim 15, whereinassigning a particular receipt receptacle to a floor of an inventorysystem based at least in part on information about the floor and theobtained information regarding inventory items contained in theparticular receipt receptacle comprises at least one of: assigning theparticular receipt receptacle to a floor based at least in part on asize of an inventory item in the particular receipt receptacle andappropriately sized storage space to accommodate the inventory item onthe assigned floor; assigning the particular receipt receptacle to afloor based at least in part on an availability of the particularreceipt receptacle to arrive for processing on the floor beforeoperators on the floor are expected to finish processing a supply ofother receipt receptacles; assigning the particular receipt receptacleto a floor based at least in part on a time that the particular receiptreceptacle was moved to a case shuttle relative to another receiptreceptacle; assigning the particular receipt receptacle to a floor basedat least in part on a proximity of a storage location for the particularreceipt receptacle to a receiving station on the floor; or assigning theparticular receipt receptacle to a floor based at least in part on afrequency of orders comprising an inventory item in the particularreceipt receptacle and at least one other inventory item stored on thefloor.
 19. The non-transitory computer-readable medium of claim 15,wherein assigning a particular receipt receptacle to a floor of aninventory system based at least in part on information about the floorand the obtained information regarding inventory items contained in theparticular receipt receptacle comprises assigning the particular receiptreceptacle to a floor based at least in part on (a) designations forgiftwrapping, additional packaging, additional labeling, and/orprocessing as an unknown item for an inventory item in the particularreceipt receptacle and (b) a presence of a station on the floorconfigured to handle inventory items with such designations).